Hi, why isn't it possible to have the devices linked over a multiway connector?

Sometimes the wiper linkage seizes and sometimes a worn link will become detached, leaving the motor running but the wipers unmoving.

It is very rare a wiper motor breaks but the switching for the self parking wears out.
Other than checking multiway connectors haven't worked loose there is little you can do without checking the supply, ground and switch and that is made much easier when there is a wiring diagram.

Your problem is vaguely similar to a problem brought to me years ago which I spent a great many hours chasing - the trouble was, the fault wasn't permanent; the car would be towed in and most of the time it would start.

To cut a long story short, the fault when I eventually found it was a single female terminal in a multiway connector that was behaving like a thermal breaker.
The design of the terminal was unfortunate - it wasn't designed to be a tight fit over the male and a sort of leaf spring was stamped into it, presumably to prevent it rattling around and to help it conduct the current flow.

The current flow was sufficient to cause some warming that over time created some oxidisation of the surface that in turn caused more warming and the little leaf spring eventually retracting and returning when things cooled down.

As was often the case it was only when the boss had lost patience and found something else to interfere with that I was able to settle down, have a couple of cigarettes and do some mindless fiddling...
I noticed one terminal in the multiway connector was a slightly different colour.

Wire colours for the audio can change depending on the manufacturer of the audio. It isn't unusual for the wire colours to change at multiway connectors.
While referring to a wiring diagram is important it is best to verify the function of each wire before making any connections.

Lamp, bulb, supply and ground obviously ok as the hazards work - I suspect the hazard switch might be faulty or something like a dodgy multiway connector onto the switch...

Depends on the design. Some are fairly simple and some are ridiculously difficult requiring the removal of the steering wheel as well as the steering column shroud.

Once the switch is removed there is the wiring to consider and again the design differs; some switches are simply plugged to the wiring and some arrive with long wire tails with multiway connectors that connect to the main wiring harness deep under the dashboard.

I suggest you suspect faulty grounding or earthing of one or more of the bulbs or lamps.

I suggest you pay particular attention to any wiring you disconnected or disturbed in the process of fitting the led lights. Multiway connector terminals are often electroplated steel prone to attack by dirt, water or damp air and such things often cause trouble after being disturbed.

Hi, It may be cheaper to buy a good condition chassis complete with wheels after looking at the price of the wheels alone. If you would like to buy 1 let me know where you live and I can get a price for you including shipping cost. Thank you

your capacitors may be blown , if its a solid state amplifier ..

if its tube version (best) , you may have blown a tube

what model number is it , manufacturer ?

Hi i bought mine from the bike department in Halfords. they are much better than the original ones!

I HAVE NOW FIXED THE PROBLEM WITH MY ELECTRIC WINDOWS AND ELECTRIC MIRRORS NOT MOVING...FRIST I CHECKED ALL FUSES (GOOD) THEN CHECKED FOR VOLTS AT THE MULTIWAY CONNECTOR ON THE A PILLAR( FULL 12V ) BUT I FOUND BROKEN WIRES JUST AS THE CABLES ENTERED INTO THE DOOR( DRIVERSIDE).......ALL FIXED NOW..